A power supply for a computer system must provide power to many peripheral components of the computer system, such as modems, compact disk drives, hard disk drives, floppy drives, SCSI drives, processors, scanners, motherboards, and the like. The power demands on a computer system power supply must be balanced with the demands of computer design and performance. Space inside the housing of a computer system is often at a premium. Thus, a computer power supply should connect to computer system components and fit into the computer system housing, without interfering with thermal needs (e.g. cooling), the operation of other components, or access to the computer system components. These requirements are particularly problematic because the overall sizes, shapes and requirements of computer components vary, and can rapidly change as technology changes. Further, there is a growing need for more compact computer systems, as well as custom and alternatively configured computer systems. Many power supplies limit the design and size of computer systems in undesirable ways.
One type of power supply has an integrated cable system, in which power output cables project from the body of the power supply. An example of this is shown in FIGS. 1 and 2. The prior art power supply 13 shown in FIG. 1 has output cable connections 10, which exit the back of the power supply in a large bundle 15. This power supply has “hardwired” cables of fixed length and the output power supplied by each cable is preset. FIGS. 2A-C show this power supply attached to a computer system. The bundle of output cables takes up considerable space within the computer system housing. Cable extenders are used to reach peripheral components that are more remotely located from the power supply. These extenders are in inconvenient and also take up valuable computer housing space. Even when the peripheral components are located close to the power supply, excess cable length clutters the computer system housing. Further, the extensive cables of such power supplies can block cooling airflow across components of the computer system.
The large bundle of output cable connections project from one general location in prior art power supplies, as shown in FIGS. 1 and 2. This results in a bulky mass of connecting wires at this location. This design does not consider the layout of the computer system, such as the location of the components. It is desirable to make more efficient connections between the components and the power supply.
Assembly time is another important consideration in manufacturing computer systems. Manufacturing time is required to attach extension cables, to tie wraps and route excess cables. In addition, servicing computer systems using power supplies such as those shown in FIGS. 1 and 2 is more difficult because of the complexity of the routing pattern required to make the connections between the power supply and the computer system components. Furthermore, a technician may have problems fitting the wires back into the computer housing.
Computer system manufacturers using such power supplies must usually stock multiple models of computer power supplies. Power supplies like the one shown in FIG. 1 have only a fixed number of cable connectors of a given output power, connector design or voltage level. Thus, computer system designs requiring different power needs require stocking another model power supply, or incorporating multiple power supplies in the design. Stocking additional power supplies can increase costs by necessitating large inventories of different designs in order to quickly assemble different types of computer systems.
Another power supply design which can be used to avoid some of these problems is the so-called “hot-swap” power supply design. In “hot-swap” power supplies, edge connectors are used to provide “modular” power supplies which connector into a fixed back-plate (also called a base module or back-plane). Computer system components are hard-wired to the back plate, avoiding the use of bulky cable connections. Unfortunately, edge connector designs are more expensive than comparable power supplies which make cable connections. Furthermore, edge connector power supplies require more space in the computer system housing because the additional power back-plate. Finally, edge connector power supplies may also be limited in the amount of current that they can handle.
Accordingly, it may be desirable to provide a power supply which allows flexibility in the kinds of connections, the locations of connections, and the output power supplied.